This invention discloses a rapid
prediction system for
crude oil SARA composition based on low-field
nuclear magnetic resonance (NMR), relating to the fields of
petrochemical analysis and energy
resource development. The
system workflow is as follows: Samples covering light, medium, heavy, and high-
asphalt crude oil are prepared and placed in tubes; LF-NMR
transverse relaxation time (T₂) spectra are acquired using CPMG sequences, and experimental parameters are standardized; the spectra are preprocessed, including normalization and
noise reduction, and features are extracted; a
partial least squares regression (PLSR) model is constructed using
column chromatography measurements as a reference, and optimized through cross-validation and
external validation; LF-
NMR data of unknown samples are input, and the
system rapidly outputs the contents of saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. This
system requires only 5-10 minutes for a single analysis, has a prediction R² exceeding 0.95, is adaptable to crude oils with different API strengths and viscosities, has no
solvent contamination, can be deployed on-site, and is suitable for oilfield development, refining optimization, and
crude oil grading and pricing scenarios.